The Central government on Wednesday said that a total of 73 persons have been detected with the new "more transmissible" UK coronavirus mutant strain, and they are being kept in physical isolation in health facilities.Out of these total cases, eight have been detected by the National Centre for Disease Control (NCDC) in Delhi, 20 at the CSIR Institute of Genomics and Integrative Biology (IGIB) in Delhi, and 11 at the National Institute of Mental Health and Neuro-Sciences (NIMHANS) in Bangaluru.Three such cases have been detected at the Cellular and Molecular Biology in Hyderabad, one at the National Institute of Biomedical Genomics in West Bengal and 30 in the National Institute of Virology, Pune.According the Health Ministry, all these persons have been kept in single room isolation in designated Health Care facilities by respective state governments. Their close contacts have also been put under quarantine."Comprehensive contact tracing has been initiated for co-travellers, family contacts and others. Genome sequencing on other specimens is going on," the ministry said.On December 29, a total of six UK returnees were found to be positive with the new variant genome. These were the first cases to be reported by the country that has the second highest number of cases after the US.The tracing and testing was initiated after the UK announced that a newly identified strain of the virus was found in their population which is up to 70 per cent more transmissible.The new UK variant has already been reported by Denmark, the Netherlands, Australia, Italy, Sweden, France, Spain, Switzerland, Germany, Canada, Japan, Lebanon and Singapore.From November 25 to December 23 midnight, about 33,000 passengers disembarked at various Indian airports from UK. All these passengers are being tracked and subjected by states and UTs to RT-PCR tests.The Union Health Ministry further stated that the situation is under careful watch and regular advice is being provided to the states for enhanced surveillance, containment, testing and dispatch of samples to labs.